| dc.description.abstract |
The Yangtze River has always been considered an important river for transporting
microplastics into the sea. However, there is still a lack of understanding of the degree
of microplastic pollution in the sediment of the middle and lower reaches of the Yangtze
River, which has affected the estimation of microplastic flux into the sea. In this study,
microplastics in sediments from 55 stations in the middle and lower reaches of the
Yangtze River were investigated, including 48 mainstream stations, 5 confluence
stations, and 2 lake stations. Microplastics were detected in 34 stations, ranging from 0
to 71.04 n/kg of dry weight. The average concentrations of microplastics in the
mainstream, confluence and lake were 6.16±8.87, 23.91±11.2, and 43.95±27.09 n/kg
of dry weight, respectively. Of all the microplastics found in this investigation, fiber
(59.52%) forms the main type in terms of shape; PET is the most abundant microplastic
species, accounting for 51.19%. Sewage treatment plants are the most likely source of
microplastics in sediment, and sediment from tributary estuaries, lake mouths, and lakes
is an important sink of microplastics. Terrain, sediment transport load, biofilm, and
flow velocity are important factors affecting microplastic settlement. Although there
are multiple microplastic enrichment areas, the high flow velocity during the flood
season makes it difficult for microplastics to remain in the sediment of the Yangtze
River bed. This indicates that microplastics in riverbed sediments have little influence
on the flux into the sea during flood season. This study is the first large-scale
investigation of microplastics in riverbed sediments in the Yangtze river basin. |
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